| Term | Definition |
| Islam | Majpr world religion having its origins in 610 C.E. in the Arabian peninsula; meaning literally submission; based on prophecy of Muhammad. |
| Muslim | follower of Islam |
| Quran | Recitations of revelations received by Muhammad; holy book of Islam |
| Hadith | Traditions of the prophet Muhammad |
| Bedouin | Nomadic pastoralists of the Arabian peninsula; culture based on camel and goat nomadism; early converts to Islam. |
| Umma | Community of the faithful within Islam; transcended old tribal boundaries to create degree of political unity |
| Caliph | The political and religious successor to Muhammad |
| Sunnis | Political and theological division within Islam. |
| Shi'is | Also known as the Shi'a and Shi'ites; political and theological followers within Islam; Followers of Ali |
| Mawali | non- Arab converts to Islam |
| Dhimmi | Literally "people of the book"; applied as inclusive term to Jews and Christians in Islamic territories; later extended to Zoroastrians and even Hindus |
| Harem | the part of a Muslim palace or house reserved for the residence of women. |
| Ayan | the wealthy landed elite that emerged in the early decades of Abbasid rule |
| Mecca | a city in West Saudi Arabia: birthplace of Muhammad; spiritual center of Islam |
| Medina | Also known as Yathrib; town located northeast of Mecca; grew date palms whose fruit was sold to bedouins; became refuge for Muhammad following flight from Mecca (hijra) |
| Umayyad | Clan of bedouins who controlled Mecca in 7th century C.E. that dominated politics and commercial economy of Mecca; clan later able to establish dynasty as rulers of Islam. |
| Ka'ba | Most revered religious shrine in pre-Islamic Arabia; located in Mecca; focus of obligatory annual truce among bedouin tribes; later incorporated as important shrine in Islam. |
| Zakat | Tax for charity; obligatory for all Muslims. |
| Five Pillars | the obligatory religious duties of all Muslims; confession of faith, prayer, fasting during Ramadan, zakat, and hajj |
| Ali | Cousin and son-in-law of Muhammad; one of the orthodox caliphs; focus for Shi'a |
| Abu Bakr | One of Muhammad's earliest converts; succeeded Muhammad as first caliph of Muslim community |
| Ridda | wars that followed muhammad's death in 632; resulted in defeat of rival prophets and some of larger clans; restored unity of Islam |
| Jihad | Struggle often used for wars in defense of the faith |
| Hijra | the flight of Muhammad from Mecca to Medina to escape persecution a.d. 622: regarded as the beginning of the Muslim Era. |
| Uthman | Third caliph and member of Umayyad clan; murdered by mutinous warriors returning from Egypt; death set off civil war in Islam between followers of Ali and the Umayyad clan |
| Siffin | fought in 657 between forces of Ali and Umayyads; settled by negotiation that led to fragmentation of Ali's party |
| Mu'awiya | Leader of Umayyad clan; first Umayyad caliph following civi war with Ali. |
| Karbala | Site of defeat and death of Husayn, son of Ali; marked beginning of Shi'a resistance to Umayyad caliphate |
| Jizya | head tax paid by all nonbelievers in Islamic territories |
| Abbasids | a member of a dynasty of caliphs ruling at Baghdad, a.d. 750–1258, governing most of the Islamic world and claiming descent from Abbas, uncle of Muhammad. |
| Wazir | helper ("right-hand man") for a high-ranking political (and sometimes religious) advisor or minister, often to a Muslim monarch such as a Caliph or Sultan. |